I believe when you split vertically, such as Guillows does, you are then building on the keel rather than the crutch. However, that's just symantics as the process is the same either way. Most, if not all, of the Top Flite scale kits are built on a crutch. When building on a crutch it usually is an integral part of the fuse but not always. I think some of Jim Ryan's electric warbirds are built on a crutch which is removed after the fuselage is sheeted. I prefer to build my fuselages on a crutch in upper and lower halves as Les described, actually pinning the crutch pieces to my building board rather than suspending them. I find it easier to build a straight fuselage this way but that is just my personal preference. I've gotten to the point that, if whatever I'm building is not designed to be built in upper and lower halves, I will often modify it so that it is. (Assuming it is not a box fuselage.) Once you get comfortable with a process why change it?